Turkey's stock exchange dropped 0.64 percent, or 636.64 points, to open at 98,727.15 points on Wednesday.
On the third transaction day of the week, the banking and holding sector indices decreased 0.66 percent and 0.53 percent, respectively.
Among all sector indices, the telecommunication sector index only posted an increase, up 0.01 percent, while the leasing factoring sector index saw the worst drop, down 2.41 percent.
On Tuesday, Borsa Istanbul's BIST 100 fell below 100,000 points for the first time in the past 11 months. The market closed at 99,363.79, down 1.49 percent, or 1,502.45 points, with a 6.8 billion Turkish lira ($1.58 billion) trade volume.
The BIST 100 was at 104,725.74 points at the beginning of the current month and 117,524.20 points at the beginning of the year.
The U.S. dollar/Turkish lira exchange rate hit all time high with 4.3720 as of 9.30 a.m. local time (0630GMT) on Wednesday, rising 1.7 percent from 4.2980 at Tuesday's close.
The euro/lira exchange rate rose 1.6 percent to reach 5.1780 by market open — from 5.0960 at the previous close — and one British pound traded for 5.9020 Turkish liras versus 5.8140 at the previous close.
The price of Brent oil climbed nearly 1.5 percent to $76.54 per barrel as of 09.30 a.m. local time (0630GMT) Wednesday, compared to $75.41 on Tuesday.